Temperature Regulating Refrigeration Systems for Varying Loads

ABSTRACT

A refrigeration system includes a compressor, a condenser, a heat transfer component, and a refrigerant loop arranged to allow a flow of a refrigerant fluid. The compressor, the condenser, and the heat transfer component are connected in the refrigerant loop. The system further includes a bypass path extending between an output side of the compressor in the refrigerant loop and an input side of the heat transfer component in the refrigerant loop. A bypass valve is connected in the bypass path. A control circuit is in communication with the bypass valve. The control circuit is configured to open the bypass valve to allow the refrigerant fluid to pass to the heat transfer component thereby increasing the refrigerant fluid provided to the heat transfer component and artificially increasing a load on the refrigeration system. Other examples refrigeration system and examples methods are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit and priority of U.S. ProvisionalPatent Application 62/901,661 filed Sep. 17, 2019. The entire disclosureof the referenced application is incorporated herein by reference.

FIELD

The present disclosure relates to temperature regulating refrigerationsystems for varying loads.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Refrigeration systems (e.g., chiller systems) commonly experiencecapacity modulation when loads on the systems vary. In such examples, arefrigeration system may include a fixed or variable speed compressorand a thermostatic expansion valve to control temperature of a coolantin the system. In cases where the refrigeration system includes avariable speed compressor, the speed of the compressor may be reducedand/or the state of the thermostatic expansion valve may be altered whena load on the system decrease (e.g., a low load condition).

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a block diagram of a refrigeration system including acontrollable bypass valve for introducing an artificial increase in aload on the refrigeration system according to one example embodiment ofthe present disclosure.

FIG. 2 is a block diagram of a refrigeration system including acompressor and a bypass valve controlled based on a sensed coolanttemperature and/or speed of the compressor according to another exampleembodiment.

FIG. 3 is a flow diagram of a control process for controlling the bypassvalve shown in FIG. 2 according to yet another example embodiment.

FIG. 4 is a schematic diagram of a refrigeration system including acompressor, a bypass valve, and an expansion valve according to anotherexample embodiment.

FIG. 5 is a flow diagram of a control process for controlling theexpansion valve shown in FIG. 4 according to yet another exampleembodiment.

FIG. 6 is a front isometric view of a refrigeration system including thecompressor, the bypass valve and the expansion valve shown in FIG. 4according to another example embodiment.

FIG. 7 is a left side front isometric view of the refrigeration systemshown in FIG. 6.

FIG. 8 is a right side view of the refrigeration system shown in FIG. 6.

FIG. 9 is a left side rear isometric view of the refrigeration systemshown in FIG. 6.

FIG. 10 is a graph of a waveform representing a temperature of a coolantfluid in the refrigeration system shown in FIG. 4 as a load on thesystem varies over time according to yet another example embodiment.

FIG. 11 is a graph of waveforms representing duty cycles of variouscomponents in the refrigeration system shown in FIG. 4 as a load on thesystem varies over time according to another example embodiment.

Corresponding reference numerals indicate corresponding (though notnecessarily identical) parts and/or features throughout the severalviews of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

As recognized herein, refrigeration systems (e.g., chiller systems,etc.) may compromise their effectiveness when thermal loads vary. Attypical thermal loads, compressors in the refrigeration systems may varytheir speed for temperature control. For example, as a thermal loaddecreases on a refrigeration system, the speed of its compressor mayalso decrease. When the compressor speed drops below a definedrevolutions per minute (RPM) threshold, lubricant (e.g., oil, etc.)return to the compressor and system efficiency may reduce.

The exemplary refrigeration systems disclosed herein may set minimumspeeds at which their compressors can operate thereby ensuring the speedof the compressors is maintained at desirable levels to prevent areduction in lubrication and system efficiency. For example, and asfurther explained herein, the refrigeration systems may includecontrollable valves that introduce artificial increases in loads on therefrigeration systems to prevent the speed of the compressors fromfalling below a threshold, and provide precise temperature regulation,control, etc. of cooling mediums (e.g., coolant fluid, etc.) in therefrigeration systems over wide load capacity ranges.

For example, a refrigeration system according to one example embodimentof the present disclosure is illustrated in FIG. 1 and indicatedgenerally by reference number 100. As shown in FIG. 1, the refrigerationsystem 100 includes a refrigerant loop 102 to allow a flow of arefrigerant fluid, a compressor 104, a condenser 106, a heat transfercomponent 108, a bypass path 110, a bypass valve 112 connected in thebypass path 110, and a control circuit 114 in communication with thebypass valve 112.

The compressor 104, the condenser 106, and the heat transfer component108 are connected in the refrigerant loop 102. The refrigerant fluidflowing through the refrigerant loop 102 passes through the compressor104, the condenser 106, and the heat transfer component 108 such thatthe refrigerant fluid flows from the compressor 104, to the condenser106, and then to the heat transfer component 108. For example, thecompressor 104 compresses the refrigerant fluid into a gas, thecondenser 106 receives and condenses the compressed refrigerant fluid(e.g., gas) from the compressor 104 into a liquid, and the heat transfercomponent 108 receives the condensed refrigerant fluid from thecondenser 106. As shown in FIG. 1, the refrigerant loop 102 forms anenclosed loop.

The bypass path 110 of FIG. 1 extends between an output side of thecompressor 104 and an input side of the heat transfer component 108. Thebypass path 110 allows the compressed refrigerant fluid (e.g., gas) topass from the compressor 104 to the heat transfer component 108 via thebypass valve 112. In some examples, the bypass valve 112 (and/or theother bypass valves disclosed herein) may be considered a hot gas bypassvalve.

The control circuit 114 controls the state of the bypass valve 112 toallow or not allow the compressed refrigerant fluid to pass from thecompressor 104 to the heat transfer component 108. For example, thecontrol circuit 114 may open and/or close the bypass valve 112 when oneor more parameters are met. The bypass valve 112 is opened to increasethe refrigerant fluid provided to the heat transfer component 108, andartificially increase a load on the refrigeration system 100. As aresult, the speed of the compressor 104 may remain substantially steadyor increase. As such, the compressor speed may remain at or abovedesirable levels to prevent a reduction in lubrication and systemefficiency.

The control circuit 114 opens and/or closes the bypass valve 112 basedon various parameters. For example, the control circuit 114 may openand/or close the bypass valve 112 based on heat transferred from athermal load component to the system 100, the compressor's speed,temperature(s) in the system 100, etc.

In some examples, the refrigeration systems disclosed herein may includea coolant loop in thermal communication with the refrigerant loop 102.For example, FIG. 2 illustrates a refrigeration system 200 substantiallysimilar to the refrigeration system 100 of FIG. 1, but including acoolant loop 216. Specifically, the refrigeration system 200 of FIG. 2includes the refrigerant loop 102, the compressor 104, the condenser106, and the heat transfer component 108 of FIG. 1, and the coolant loop216 to allow a flow of a coolant fluid. As shown in FIG. 2, the heattransfer component 108 is connected in the coolant loop 216 (in additionto the refrigerant loop 102). This allows the heat transfer component108 to transfer heat from the coolant fluid in the coolant loop 216 tothe condensed refrigerant fluid in the refrigerant loop 102.

Additionally, and as shown in FIG. 2, the refrigeration system 200includes a thermal load component 218 connected in the coolant loop 216.The thermal load component 218 transfers heat (e.g., a load) to thecoolant fluid in the coolant loop 216 to cool the thermal load component218. The amount of heat transferred from the thermal load component 218(and therefore the load) to the coolant fluid may vary over timedepending on, for example, characteristics of the load component 218,operating parameters of the load component 218, surrounding environment,etc. At least some of the heat in the coolant fluid (e.g., heat from thethermal load component 218) is transferred to the condensed refrigerantfluid in the refrigerant loop 102 to cool the coolant fluid in thecoolant loop 216. The amount of heat transferred to the refrigerantfluid in the refrigerant loop 102 may depend on, for example, thetemperature of the refrigerant fluid. As explained above, the speed ofthe compressor 104 may vary for controlling the temperature of therefrigerant fluid (and therefore the coolant loop 216). As such, achange in the heat transferred from the thermal load component 218 mayresult in a change in the compressor's speed.

In some examples, the control circuit 114 of FIG. 2 may control a stateof the bypass valve 112 based on a temperature of the coolant fluid inthe coolant loop 216. For example, and as shown in FIG. 2, the system200 may include a temperature sensor 220 in communication (e.g., awireless and/or wired connection) with the control circuit 114. Thetemperature sensor 220 is connected in the coolant loop 216 for sensingthe temperature of the coolant fluid. The temperature sensor 220 maysend one or more signals (the dashed line 222 of FIG. 2) representingthe sensed temperature to the control circuit 114. As such, the controlcircuit 114 may determine the temperature of the coolant fluid (e.g.,based on the received signals from the temperature sensor 220), and openand/or close the bypass valve 112 based on the determined temperature.For example, the control circuit 114 may open the bypass valve 112 inresponse to the determined temperature being less than or equal to adefined temperature threshold (e.g., a setpoint temperature).

Additionally and/or alternatively, the control circuit 114 may controlthe state of the bypass valve 112 based on a speed of the compressor104. For example, the control circuit 114 may receive one or moresignals (the dashed line 224 of FIG. 2) representing the speed of thecompressor 104. In some examples, the compressor 104 may include and/orbe in communication with a tachometer for measuring the RPM of thecompressor 104. The control circuit 114 may receive these signals via awireless connection and/or wired connection. The control circuit 114 maydetermine a speed of the compressor 104 (e.g., based on the receivedsignals), and open and/or close the bypass valve 112 based on thedetermined speed. For example, the control circuit 114 may open thebypass valve 112 in response to the determined speed being less than orequal to a defined speed threshold.

In other examples, the control circuit 114 of FIG. 2 may control a stateof the bypass valve 112 based on the heat transferred from the thermalload component 218. For example, if the amount of heat transferred(e.g., the load) from the thermal load component 218 is reduced, thecompressor 104 may begin to decrease its speed accordingly. However, ifthe control circuit 114 detects the reduction of the heat transferredfrom the thermal load component 218, the control circuit 114 may openthe bypass valve 112 to increase the refrigerant fluid provided to theheat transfer component 108, and artificially increase the load on thesystem 200, as explained above.

FIG. 3 illustrates an example control process 300 of the control circuit114 of FIG. 2 for controlling the state of the bypass valve 112. Asshown in FIG. 3, the process 300 begins by sensing a temperature of thecoolant fluid (e.g., via the temperature sensor 220) in block 302, andcomparing the sensed temperature of the coolant fluid to a definedtemperature threshold (e.g., a setpoint temperature) T_set in block 304.If the sensed temperature of the coolant fluid is greater than thedefined temperature threshold T_set, the control circuit 114 determinesif the bypass valve 112 is open in block 306. If the bypass valve 112 isclosed, the speed of the compressor 104 may be increased and/or asuperheat condition of the refrigerant fluid in the refrigerant loop 102may be maintained (as further explained below) in block 308, and theprocess 300 returns to sensing a temperature of the coolant fluid inblock 302. The speed of the compressor 104 and/or the superheatcondition may be controlled by the control circuit 114 if desired. Forexample, and as shown in FIG. 2, the control circuit 114 may provide acontrol signal 226 to the compressor 104 to control the speed of thecompressor 104. In such examples, a compressor drive speed input signalmay adjust the power output to the compressor 104 based on the controlsignal 226 to increase and/or decrease the speed of the compressor 104.

In some examples, the control circuit 114 may close the bypass valve 112in response to the determined temperature being greater than the definedtemperature threshold T_set. For example, and as shown in FIG. 3, if thecontrol circuit 114 determines the sensed temperature of the coolantfluid is greater than the defined temperature threshold T_set in block304, and the bypass valve 112 is open in block 306, the control circuit114 may close the bypass valve 112 in block 310. After which, the speedof the compressor 104 may be increased and/or the superheat condition ofthe refrigerant fluid may be maintained in block 308. The process 300then returns to sensing a temperature of the coolant fluid in block 302.

If the control circuit 114 determines that the sensed temperature of thecoolant fluid is less than or equal to the defined temperature thresholdT_set in block 304, the control circuit 114 compares a determined speedof the compressor 104 with a defined speed threshold S_set in block 312.If the determined compressor speed is greater than the defined speedthreshold S_set, the speed of the compressor 104 is decreased in block314, and the process 300 returns to sensing a temperature of the coolantfluid in block 302. Alternatively, the control circuit 114 determinesthe speed of the compressor is less than or equal to the defined speedthreshold S_set, the bypass valve 112 is opened in block 316. Afterwhich, the process 300 returns to sensing a temperature of the coolantfluid in block 302.

FIG. 4 illustrates a refrigeration system 400 similar to therefrigeration system 200 of FIG. 2, but including an evaporator as aheat transfer component. For example, the refrigeration system 400includes a refrigerant loop 402, a compressor 404, a condenser 406, anevaporator 408, a bypass path 410, and a bypass valve 412 connected inthe bypass path 410. As shown, the compressor 404, the condenser 406,and the evaporator 408 are connected in the refrigerant loop 402.

Additionally, and as shown in FIG. 4, the refrigeration system 400includes a coolant loop 416 in thermal communication with therefrigerant loop 402, a coolant tank 436, and a pump 438. The coolanttank 436 and the pump 438 are connected in the coolant loop 416. Thepump 438 and the coolant tank 436 facilitate cooling of a thermal loadcomponent (not shown) connected in the coolant loop 416. The pump 438generates a coolant fluid flow in the coolant loop 416. The coolant tank436 is a fluid reservoir that stores coolant fluid as the coolant fluidis cycling through the coolant loop 416. The coolant tank 436 mayinclude a coolant inlet to allow a user to add coolant fluid if desired.

The refrigerant loop 402 and the coolant loop 416 are similar to therefrigerant loop 102 and the coolant loop 216 explained above. Forexample, the evaporator 408 is connected in both the refrigerant loop402 and the coolant loop 416, and transfers heat from a coolant fluid inthe coolant loop 416 to a refrigerant fluid in the refrigerant loop 402.The coolant fluid is circulated through the thermal load component sothat the thermal load component may transfer heat (e.g., a load) to thecoolant fluid in the coolant loop 416 to cool the thermal loadcomponent.

The bypass valve 412 of FIG. 2 is similar to the bypass valve 112 ofFIGS. 1 and 2. For example, the bypass valve 412 may be controlled by aprocess similar to the control process 300 of FIG. 3. As such, a controlcircuit (e.g., the control circuit 114 of FIGS. 1 and 2, etc.) may openthe bypass valve 412 to allow compressed refrigerant fluid in therefrigerant loop 402 to pass to the evaporator 408 via the bypass path410 thereby increasing the refrigerant fluid provided to the evaporator408 and artificially increasing a load on the refrigeration system(e.g., the compressor 404). In such examples, the control circuit maycontrol the bypass valve 412 based on a determined (e.g., sensed, etc.)temperature of the coolant fluid in the coolant loop 416, a speed of thecompressor 404, etc. as explained above.

As shown in FIG. 4, the refrigeration system 400 further includes anexpansion valve 432 connected in the refrigerant loop 402 between thecondenser 406 and the evaporator 408. Specifically, the expansion valve432 is connected between the output of the condenser 406 and a pointwhere the bypass path 410 meets the refrigerant loop 402. In the exampleof FIG. 4, the expansion valve 432 may be an electronic expansion valve.As such, the expansion valve 432 may be controlled by a control circuit,as further explained below. In some examples, the same control circuitor different control circuits may be employed to control one or more ofthe compressor 404, the bypass valve 412 and/or the expansion valve 432.

Additionally, the refrigeration system 400 may optionally includevarious sensing devices for sensing, detecting, etc. parameters of thesystem 400. Some of the sensors may be connected in and/or incommunication with the refrigerant loop 402, and other sensors may beconnected in and/or in communication with the coolant loop 416. Datafrom one or more of the sensing devices may be used in controlling thecompressor 404, the bypass valve 412 and/or the expansion valve 432 asexplained herein.

For example, and as shown in FIG. 4, the system 400 includes temperaturesensors 446, 450, 454, pressure sensors 440, 448, 452, and a moisturesensor 444. The temperature sensor 446 is positioned on the suction side(e.g., the input side) of the compressor 404 for sensing a temperaturein the refrigerant loop 402, the temperature sensor 450 is positioned onthe return side of the thermal load component, and the temperaturesensor 454 is positioned on the supply side of the thermal loadcomponent. The pressure sensor 440 is positioned on the output side ofthe condenser 406 for sensing a pressure level of the condensedrefrigerant fluid, the pressure sensor 448 is positioned on the suctionside of the compressor 404 for sensing a pressure level of therefrigerant fluid on the input side of the compressor 404, and thepressure sensor 452 is positioned on the supply side of the thermal loadcomponent for sensing a pressure level of the coolant fluid provided tothe thermal load component. The moisture sensor 444 is positioned on theoutput side of the condenser 406 for detecting moisture in the condensedrefrigerant fluid.

Further, the refrigeration system 400 may optionally include one or moredevices for drying, filtering, etc. fluid in the system 400. Forexample, the refrigeration system 400 of FIG. 4 includes a combineddrying and filtering device 442. As shown, the device 442 is connectedin and/or in communication with the refrigerant loop 402 between themoisture sensor 444 and the output side of the condenser 406. The device442 may filter containments and/or remove moisture in the condensedrefrigerant fluid provided by the condenser 406.

The state of the expansion valve 432 may be controlled based on one ormore parameters of the refrigeration system 400. For example, FIG. 5illustrates a control process 500 of a control circuit for controllingthe state of the expansion valve 432. As shown in FIG. 5, the process500 begins by collecting data in block 502. The collected data mayrelate to parameters of the refrigeration system 400 such astemperatures, pressure levels, etc. For example, the control circuit maydetermine a temperature on the suction side of the compressor 404 basedon one or more signals from the temperature sensor 446, a pressure levelon the suction side of the compressor 404 based on one or more signalsfrom the pressure sensor 448, a refrigerant saturation temperature, etc.The refrigerant saturation temperature may be determined (e.g.,calculated, etc.) by the control circuit based on thermodynamicproperties of the system 400, stored lookup tables, etc.

After the data is collected in block 502, the control circuit maycalculate the superheat of the refrigerant fluid in block 504. Forexample, the superheat may be calculated by subtracting the refrigerantsaturation temperature from the suction side temperature, both of whichare determined in block 502. The control circuit then compares thecalculated superheat with a defined temperature threshold T_set2 inblock 506. The defined temperature threshold T_set2 may be set to adetermined superheat value that may vary for different refrigerationsystems. For example, the superheat represents the additionaltemperature to which a refrigerant is heated beyond its saturated vaportemperature. Saturated vapor temperature is the temperature where all ofthe liquid refrigerant is converted to vapor. This ensures that onlyvapor refrigerant enters the compressor. The defined temperaturethreshold T_set2 may be set to any suitable value based oncharacteristics of its corresponding refrigeration system. For example,the defined temperature threshold T_set2 may be 10° C., 15° C., etc.

If the superheat is less than the temperature threshold T_set2 in block506, the control circuit may close the expansion valve 432 in block 508.Alternatively, if the superheat is greater than or equal to thetemperature threshold T_set2 in block 506, the control circuit may openthe expansion valve 432 in block 510. After the expansion valve 432 isopened or closed, the process 500 returns to collecting data in block502.

The valves disclosed herein may be opened and/or closed by motors thatare controlled by a control circuit (e.g., the control circuit 114 ofFIGS. 1 and 2, etc.). For example, and as shown in FIG. 4, therefrigeration system 400 may optionally include motors 430, 434 incommunication with the valves 412, 432, respectively, and the controlcircuit referenced above relative to FIG. 4. In such examples, themotors 430, 434 may change the state of the valves 412, 432 wheninstructed by the control circuit.

In some examples, the valves may be fully opened, fully closed,partially opened and/or partially closed. In such examples, the motors430, 434 may be stepper motors that move the valves 412, 432 open and/orclose in steps. As such, the motor 430 may be controlled to partiallyopen the bypass valve 412 if a coolant temperature and a compressorspeed conditions are met (e.g., as described above relative to blocks304, 312 of FIG. 3), further open the bypass valve 412 if the coolanttemperature and the compressor speed conditions are met again, partiallyclose the bypass valve 412 if another coolant temperature condition ismet, further close the bypass valve 412 if the other coolant temperaturecondition is met again, etc. Likewise, the motor 434 may be controlledto partially open the expansion valve 432 if a superheat condition ismet (e.g., as described above relative to block 506 of FIG. 5), furtheropen the expansion valve 432 if the superheat condition is met again,partially close the expansion valve 432 if another superheat conditionis met, further close the expansion valve 432 if the other superheatcondition is met again, etc. This may allow for more precise controlover the amount of compressed refrigerant fluid flowing through thebypass path 410 and/or the amount of refrigerant fluid flowing throughthe refrigerant loop 402.

FIGS. 6-9 illustrate a refrigeration system 600 including the componentsof the refrigeration system 400 of FIG. 4 housed in an enclosure 660.For example, and as shown in FIGS. 6-9, the compressor 404, thecondenser 406, the evaporator 408, the bypass valve 412, the expansionvalve 432, the coolant tank 436, and the pump 438 of FIG. 4 arepositioned in the enclosure 660. Additionally, and as shown in FIG. 8,the refrigeration system 600 includes a control board 662 (e.g., aprinted circuit board) and a power board 664 for controlling andpowering components in the system 600. For example, the power board 664may include a variable-frequency drive (VFD) and/or another suitabledrive for powering the compressor 404. Additionally, the control board662 may include control circuitry for controlling the bypass valve 412,the expansion valve 432 and the compressor 404 (e.g., via the VFD), asexplained herein.

As shown in FIGS. 6-9, the refrigeration system 600 may include variousoptional components, such as a coolant inlet 666, a display 668, andconnections for coupling to a thermal load component (not shown), etc.For example, the coolant inlet 666 is in fluid communication with thecoolant tank 436 for allowing a user to add coolant fluid if desired.The display 668 may provide user data, characteristics of the system600, etc. In some examples, the display 668 may include a touch screenfor receiving user input such as system parameters, etc. The connectionsfor coupling to the thermal load component include an inlet 670 forreceiving the coolant fluid from the thermal load component and outlet672 for providing the coolant fluid to the thermal load component.

The condensers disclosed herein may be any suitable condenser. In someexamples, the condensers may include one or more coils and fans. Forexample, the condenser 406 includes coils 428 and a fan 426, as shown inFIGS. 4, 8 and 9. In such examples, the fan 426 may push or pull airthrough the coils to cool the refrigerant fluid. The fan 426 may becontrolled with the same or a different control circuit that controlsother components (e.g., the compressor 404, the bypass valve 412, theexpansion valve 432, etc.) in the refrigeration system 400. In someexamples, the fan 426 may be an axial fan, and the coils may be formedof aluminum.

The compressors disclosed herein may be any suitable compressor. Forexample, any one of the compressors may include a variable speedcompressor. In such examples, a frequency control (e.g., a VFD, etc.)may be used to vary the speed of the compressor if desired. In somecases, the compressors may be adapted to run substantially continuouslydue to the valves assisting in substantially maintaining, regulating,controlling, etc. the temperature of the cooling fluid at a setpointtemperature (e.g., a defined temperature threshold). As a result, thenumber of compressor on/off cycles may be reduced, and the life of thecompressors may be extended.

The heat transfer components disclosed herein may be any suitablecomponent capable of transferring heat between a refrigerant loop and acoolant loop. For example, the heat transfer components may transferheat from the coolant loop to the refrigerant loop to reduce atemperature of the coolant fluid in the coolant loop as explainedherein. The heat transfer components may include an evaporator (e.g.,the evaporator 408 of FIG. 4), a heat exchanger, etc. In some examples,the evaporator may include a heat exchanger such as brazed plate heatexchanger, etc.

The control circuits disclosed herein may include an analog controlcircuit, a digital control circuit (e.g., a microprocessor, amicrocontroller, a digital signal controller (DSC), a digital signalprocessor (DSP), etc.), or a hybrid control circuit (e.g., a digitalcontrol circuit and an analog control circuit). The control circuits maybe configured to perform (e.g., operable to perform, etc.) any of theexample processes described herein using any suitable hardware and/orsoftware implementation. For example, any one of the control circuitsdisclosed herein may include necessary hardware and/or softwarecomponents for comparing determined (e.g., sensed, etc.) parameters withdefined thresholds, controlling the states of valves, etc. In suchexamples, the control circuits may execute computer-executableinstructions stored in a memory, may include one or more logic gates,control circuitry, etc.

By employing any one of the controllable valves disclosed herein,precise temperature control of cooling mediums in the refrigerationsystems (e.g., chiller systems, etc.) over wide load capacity ranges maybe obtained without compromising compressor lubrication. As such, therefrigeration systems disclosed herein may experience increased systemefficiency (e.g., coefficient of performance).

By way of example, FIGS. 10 and 11 illustrate graphs 1000, 1100including waveforms representing various parameters of the refrigerationsystem 400 of FIG. 4 when the load on the system 400 varies over time.Specifically, the graph 1000 of FIG. 10 includes a waveform 1002representing the temperature (in Celsius) of the coolant fluid in thecoolant loop 416. As shown in FIG. 10, the temperature of the coolantfluid remains substantially constant at about 20° C. (e.g., a setpointtemperature) when the load changes between 1.2 kW, 0.8 kW and 0.5 kW.

The graph 1100 of FIG. 11 includes waveforms 1102, 1104, 1106, 1108representing duty cycles of the compressor 404, the condenser fan 426,the expansion valve 432, and the bypass valve 412 of FIG. 4,respectively. As shown in FIG. 10, when the load drops to 0.5 kW (e.g.from 0.8 kW), the temperature of the coolant fluid falls below thesetpoint temperature of 20° C. As a result, the duty cycle of thecompressor 404 and the duty cycle of the condenser fan 426 reduce, asshown by the waveforms 1102, 1104 of FIG. 11. As such, the compressor404 is operated (e.g., turned on) less as the load drops causing thecompressor speed to decrease. Additionally, during this time, theexpansion valve 432 begins to close in steps and the bypass valve 412beings to open in steps, as shown by the waveforms 1106, 1108 of FIG.11. This causes the load on the refrigeration system 400 to artificiallyincrease to prevent the compressor speed to decrease further, asexplained herein. As a result, the temperature of the coolant fluid maybe controlled at about the setpoint temperature of 20° C., as shown inFIG. 10. When the load reaches 0.8 kW and 1.2 kW, the duty cycle of thecompressor 404 and the duty cycle of the condenser fan 426 increase, theexpansion valve 432 is open, and the bypass valve 412 is closed, asshown by the waveforms 1102, 1104, 1106, 1108 of FIG. 11.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms, and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail. In addition, advantages and improvements that maybe achieved with one or more exemplary embodiments of the presentdisclosure are provided for purposes of illustration only and do notlimit the scope of the present disclosure, as exemplary embodimentsdisclosed herein may provide all or none of the above mentionedadvantages and improvements and still fall within the scope of thepresent disclosure.

Specific dimensions, specific materials, and/or specific shapesdisclosed herein are example in nature and do not limit the scope of thepresent disclosure. The disclosure herein of particular values andparticular ranges of values for given parameters are not exclusive ofother values and ranges of values that may be useful in one or more ofthe examples disclosed herein. Moreover, it is envisioned that any twoparticular values for a specific parameter stated herein may define theendpoints of a range of values that may be suitable for the givenparameter (i.e., the disclosure of a first value and a second value fora given parameter can be interpreted as disclosing that any valuebetween the first and second values could also be employed for the givenparameter). For example, if Parameter X is exemplified herein to havevalue A and also exemplified to have value Z, it is envisioned thatparameter X may have a range of values from about A to about Z.Similarly, it is envisioned that disclosure of two or more ranges ofvalues for a parameter (whether such ranges are nested, overlapping ordistinct) subsume all possible combination of ranges for the value thatmight be claimed using endpoints of the disclosed ranges. For example,if parameter X is exemplified herein to have values in the range of1-10, or 2-9, or 3-8, it is also envisioned that Parameter X may haveother ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3,3-10, and 3-9.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. Forexample, when permissive phrases, such as “may comprise”, “may include”,and the like, are used herein, at least one embodiment comprises orincludes the feature(s). As used herein, the singular forms “a,” “an,”and “the” may be intended to include the plural forms as well, unlessthe context clearly indicates otherwise. The terms “comprises,”“comprising,” “including,” and “having,” are inclusive and thereforespecify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. The method steps,processes, and operations described herein are not to be construed asnecessarily requiring their performance in the particular orderdiscussed or illustrated, unless specifically identified as an order ofperformance. It is also to be understood that additional or alternativesteps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A refrigeration system comprising: a refrigerantloop arranged to allow a flow of a refrigerant fluid; a compressorconnected in the refrigerant loop to compress the refrigerant fluid; acondenser connected in the refrigerant loop to receive the compressedrefrigerant fluid from the compressor and condense the compressedrefrigerant fluid; a heat transfer component connected in therefrigerant loop to receive the condensed refrigerant fluid from thecondenser; a bypass path extending between an output side of thecompressor in the refrigerant loop and an input side of the heattransfer component in the refrigerant loop to pass the compressedrefrigerant fluid from the compressor to the heat transfer component; abypass valve connected in the bypass path; and a control circuit incommunication with the bypass valve, the control circuit configured toopen the bypass valve to allow the compressed refrigerant fluid to passto the heat transfer component thereby increasing the refrigerant fluidprovided to the heat transfer component and artificially increasing aload on the refrigeration system.
 2. The refrigeration system of claim 1further comprising a coolant loop arranged to allow a flow of a coolantfluid, the heat transfer component connected in the coolant loop totransfer heat from the coolant fluid to the condensed refrigerant fluid.3. The refrigeration system of claim 2 further comprising a thermal loadcomponent configured to connect in the coolant loop and transfer heat tothe coolant fluid in the coolant loop to cool the thermal loadcomponent.
 4. The refrigeration system of claim 3 wherein the controlcircuit is configured to control a state of the bypass valve based onthe heat transferred from the thermal load component.
 5. Therefrigeration system of claim 4 further comprising a motor incommunication with the control circuit and the bypass valve, the motorconfigured to change the state of the bypass valve when instructed bythe control circuit.
 6. The refrigeration system of claim 2 wherein thecontrol circuit is configured to determine a temperature of the coolantfluid and open the bypass valve in response to the determinedtemperature being less than or equal to a defined temperature threshold.7. The refrigeration system of claim 6 wherein the control circuit isconfigured to determine a speed of the compressor and open the bypassvalve in response to the determined speed being less than or equal to adefined speed threshold.
 8. The refrigeration system of claim 6 whereinthe control circuit is configured to close the bypass valve in responseto the determined temperature being greater than the defined temperaturethreshold.
 9. The refrigeration system of claim 1 further comprising anelectronic expansion valve connected in the refrigerant loop between thecondenser and the heat transfer component, the control circuitconfigured to control a state of the electronic expansion valve based onone or more parameters of the refrigeration system.
 10. Therefrigeration system of claim 9 further comprising a motor incommunication with the control circuit and the electronic expansionvalve, the motor configured to change the state of the electronicexpansion valve when instructed by the control circuit.
 11. Therefrigeration system of claim 10 wherein the compressor includes avariable speed compressor.
 12. The refrigeration system of claim 1wherein the heat transfer component includes an evaporator.
 13. A methodof altering a load on a refrigeration system including a refrigerantloop arranged to allow a flow of a refrigerant fluid, a compressorconnected in the refrigerant loop to compress the refrigerant fluid, acondenser connected in the refrigerant loop to receive the compressedrefrigerant fluid from the compressor and to condense the compressedrefrigerant fluid, a heat transfer component connected in therefrigerant loop to receive the condensed refrigerant fluid from thecondenser, a bypass path extending between an output side of thecompressor in the refrigerant loop and an input side of the heattransfer component in the refrigerant loop to pass the compressedrefrigerant fluid from the compressor to the heat transfer component,and a bypass valve connected in the bypass path, the method comprising:opening a bypass valve to allow the compressed refrigerant fluid to passto the heat transfer component thereby increasing the refrigerant fluidprovided to the heat transfer component and artificially increasing aload on the refrigeration system.
 14. The method of claim 13 wherein:the refrigeration system includes a coolant loop having a coolant fluid;the heat transfer component is connected in the coolant loop to transferheat from the coolant fluid to the condensed refrigerant fluid; andopening the bypass valve includes opening the bypass valve based on heattransferred from a thermal load component when the thermal loadcomponent is connected to the coolant loop.
 15. The method of claim 13wherein: the refrigeration system includes a coolant loop having acoolant fluid; the heat transfer component is connected in the coolantloop to transfer heat from the coolant fluid to the condensedrefrigerant fluid; and opening the bypass valve includes opening thebypass valve in response to a temperature of the coolant fluid beingless than or equal to a defined temperature threshold.
 16. The method ofclaim 15 further comprising closing the bypass valve in response to thetemperature being greater than the defined temperature threshold. 17.The method of claim 16 wherein opening the bypass valve or closing thebypass valve includes opening or closing the bypass valve via a motorcoupled to the bypass valve.
 18. The method of claim 13 wherein openingthe bypass valve includes opening the bypass valve in response to aspeed of the compressor being less than or equal to a defined speedthreshold.
 19. The method of claim 13 wherein the compressor includes avariable speed compressor.
 20. The method of claim 13 wherein the heattransfer component includes an evaporator.